Go to Market Pro Max –> Optimizer
This tool will allow you to run conversion tests on your site. To use the tool you set a control page, a variation page and a goal page. So an example of that would be your optin page, a variation of your optin page, and the goal page would be your thank you page.
Once this is set, the Market Pro Max system will control what page is displayed to visitors of your website. When they visit the link to your control page, they could land on either the control page or the variation page. Once this is running Market Pro Max will start collecting conversion test results.